Magnetic separator



April 2, 196s J, H. CARPENTER 3,375,925

MAGNETIC SEPARATOR 4 Sheecs-Sheefv l INVENTOR.

JAMES HALL CARPENTER Filed oct, 1s, 196e April 2 1968 J. H. CARPENTER 3,375,925

MAGNETIC SEPARATOR Filed Oct. 18, 1966 4 Sheets-Sheet 2 H03 HH@ /23 NoN MAGNEUC WASH WATER MATERIAL INVENTOR JAMES HALL CARPENTER BY MAGNETIC NoN MAGNEnc rMATERIAL v MATERIAL J4/MJL /ifg A TTORNEY' April 2, 196s J. H. CARPENTER 3,375,925

MAGNETIC SEPARATOR Filed Oct. 18, 1966 4 Sheets-Sheet 5 sir-I- NON MAGNETIC MATERIAL YB l l L13 l *l l MAGNETIC MATERIL INVENTOR JAMES HALL CARPENTER BY Y ,44ml M JWM; fc/17e.

A T TORNE YJ April 2, 1968 J, H. CARPENTER MAGNETIC SEPARATOR 4 Sheets-Sheet 4 Filed Oct. 18, 1966 FIG. I3.

INVENTOR JAMES HALL CARPENTER BMM/@f ATTORNEYS United States PatentfO 3,375,925 `MAGNETIC SEPARATR i James Hall Carpenter, Jacksonville, Fla., assignor to Carpco Research i 8L` Engineering, Inc., Jacksonville, Fla., a corporationof Florida Continuation-impart of application Ser. No. 335,069, Jan. 2, 1964. This applicationOct. 18,1966, Ser. No. 587,494

24 Claims. "(Cl. 209-214) ABSTRACT 0F THE- DISCLOSURE A method and an apparatus for separating materials of differing magnetic susceptibility utilizing ra plurality of loose, unattached, individually movable bodies, at least some of which are composed of a highly permeable material, wherein the bodies are successively passed into,

t through and out of an effective magnetic field.

The present application is `a continuation-in-part of copending application Ser. No. 335,069, filed Jan.,2, 1964, now abandoned.

This invention relates `to magnetic separators for separating materials of differing magnetic susceptibility, and, more particularly, to magnetic'separators adapted to separate materials of nonmagnetic susceptibility or materials lof relatively low magnetic susceptibility from materials of relatively high magnetic susceptibility.

Magnetic separators long have been known in the art and have been particularly efhcacious in the separation `of materials of high magnetic susceptibility from materials of nonmagnetic susceptibility. Although the greatest suc- `cess and commercial use of magnetic separators previously have" been accomplished utilizing dry separation processes, some ysuccess in the separation of highly magnetically susceptible materials under wet conditions has i been achieved. Despite strenuous efforts over .a long period of time, however, there has not been developed heretofore a commercially satisfactory magnetic separator for the magnetic beneficiation of weakly magnetically or nonmagnetically susceptible materials, such as weakly magnetically susceptible molybdenum and tungsten ores or nonmagnetically susceptible titanium ores, under wet conditions.

The more successful magnetic separators developed and employed in the rart usually have comprised an axially rotatable drum having disposed interiorly thereof a plurality of fixed magnets. The magnets normally are placed iin close proximity to a selected portion of the interior surface area of the drumtso that when magnetically susceptible particle-carrying material is fed against the eX- ternal `peripheral portion of the drum overlying the fixed magnets, the magnetically susceptible particles will adhere to the surface of the drum, and can thereafter be carried to a discharge position. The nonmagnetically susceptible material, unaffected by the magnetic field, normally is permitted to fall under the influence `of gravity for separate collection. When such equipment is employed for wet separatingprocesses, a slurry or pulp of the material i to be separated either is fed against the external periphery of the drum in the same manner .as dry material or, where more dilute slurries, pulps or suspensions of materials are employed as the feed, the rotating drum often is submerged in the liquid.

As indicated, processes employing such equipment have been quite successful with dry material and moderately `successful with wet material where strongly magnetically 'susceptible particles were being separated from nonmagnetically susceptible particles. Under wet conditions, how- 3,375,925 Patented Apr. 2, 1968 ever, any relative movement between the particle-carrying fluidand the magnetically actuated surface employed to effect the separation, such as the movement resulting from i the presence of` eddy currents, has tended to wash weakly magnetically susceptible particles away 'from the surface after contact has beensattained. lReduction of the rotational speed of the drum to avoid eddy currents has reduced the eiciency of the separation so that suchprocesses have been foundito be economically infeasible.

The extended efforts to solve the problem of separating weakly magnetically and nonmagnetically susceptible "materials, particularly under wet conditions, are exemplitied by Jones Patents 2,834,470 and 3,021,007. However, these and other efforts have failed tov provide the art with the practical commercial separator desired.

It is, therefore, the primary object of the present invention to provide a magnetic separator which effectively `separates weakly magnetically susceptible materials from i nonmagneticallysusceptible or faintly magneticallysusceptible materials under' both dry and wet conditions.

A further object of the invention is to provide a magnetic separator which will effectively `separate weakly magnetically susceptibleimaterials fromgangue materials in yields which are economically attractive.

Another object ofthe invention is to provide a magnetic separator which will effectively separate economically attractive yields of .a desired nonmagnetically susceptible material from feed mixtures containinghighly magnetically susceptible and weakly magnetically susceptible materials.

An additional `object of the invention is to provide a magnetic separator which is economical to construct, has

few moving parts and is readily serviceable.

Yet another object of the invention is to providea magnetic separator which does not require meticulous sizmg of feed materials` and which tends to be essentially self-cleaning.

A further object of the invention is to provide a magnetic separator in which high eld strengths of over `strates resistance` to becoming clogged or choked with 1ferromagneticimpurities which may be present in the feed Vmaterials Another object of the invention is to provide a magnetic `separator which, when utilized for the separation of desired `nonmagnetieally susceptible materials, substantially obviates entrapment of the Vnonmagnetically susceptible l materials by the highly `magnetically susceptible materials which may be present in the feed.

Yet` a further object of the invention is to provide a method for Vseparating nonmagnetically susceptible materialsor materials of relatively low magnetic susceptibility Vfrom materials. of relatively high magnetic susceptibility,

which vmethod is practical economically.

Additional objects of the invention will become apparent upon consideration of the general and detailed descriptions which follow.

Generally described, the apparatus of the present invention is a device for separating materials of differing magnetic susceptibility comprising: at least one magnet` means having oppositely disposed field poles of opposite polarity for producing an effective magnetic field therebetween; a `plurality of loose, unattached induced pole pieces movable relative to the field poles, said induced pole pieces being individually movable relative to each other; means for moving the induced pole pieces and the field poles relative to each other so that the induced pole pieces pass into, through and out of the effective magnetic field, and means for introducing the material to be separated into the effective magnetic field and therein into proximity with the induced pole pieces as the pieces pass through said field.

Generally described, the method of the present invention is a process for separating materials of nonmagnetic susceptibility or materials of relatively low magnetic susceptibility from materials of relatively high magnetic susceptibility which comprises: passing a mixture of the materials to be separated into a continuous magnetic field and therein into proximity with a plurality of individually movable bodies at least some of which are composed of a highly permeable material; removing the feed material of nonmagnetic susceptibility or lower magnetic suspectibility from proximity with the individually movable bodies and from the feed material of higher magnetic susceptibility while the feed materials and the individually movable bodies are within the continuous magnetic field; separately collecting the material of nonmagnetic susceptibility or material of lower magnetic susceptibility; removing the feed material of higher magnetic susceptibility and the individually movable bodies from the continuous magnetic field; removing the feed material of higher magnetic susceptibility from proximity with the individually movable bodies; and separately collecting the feed material of higher magnetic susceptibility.

In accordance with the present invention, an induced pole piece is a piece of highly permeable material which will become magnetized by magnetic induction when the pole piece is disposed within a magnetic field. Such a pole piece may be characterized by a number of sharp edges, corners or surfaces which will become highly inductively magnetized and will cause the fiux lines of a magnetic field in which the piece is disposed to converge, to provide optimum -points for attracting magnetically susceptible material. In the alternative, an induced pole piece may be characterized by a smooth, continuous, contour-ofrevolution configuration, having a surface which will become highly inductively magnetized at specific regions causing the flux lines of a magnetic field in which the piece is disposed to converge, and thus :also provide optimum points for attracting magnetically susceptible material. Induced pole pieces operable in the present invention include, without limitation, helical rods resembling drill bits, cubes, spheres, deformed metallic screen, expanded metal and the like.

As used in the specification and claims, the phrase effective magnetic field defines a spatial region within which the strength of the magnetic field produced by a magnet means is of sufficient magnitude to cause an induced pole piece disposed therein to become inductively magnetized to such a degree that any substantial amount of magnetically susceptible material present in the feed material will be attracted by such induced pole piece.

The magnet means operable in the apparatus and method of the invention, for producing effective magnetic fields, may comprise either electromagnets or permanent magnets. Because of their greater strength, electromagnets are preferred. The magnet cores, magnet field poles and induced pole pieces may be fabricated from any highly permeable material. Preferably these members are fabricated from low carbon steel or an alloy of iron and cobalt. In particular, the induced pole pieces preferably are fabricated from a magnetically soft material to minimize any tendency of the induced pole pieces to become permanently magnetized.

In accordance with a preferred embodiment of the invention, a plurality of loose, unattached, individually movable induced pole pieces are Carried by an annular container rotatably mounted to pass between the field poles of one or more magnet means. Alternately, the induced pole pieces may be disposed within a container which is mounted to pass between the field poles of one or more magnet means in a substantially straight line or in an arcuate path. Whether the induced pole pieces are passed between the field poles of the magnet means in a curvilinear or straight line, such passage through the effective magnetic field or fields produced by the magnet means may be reciprocal. ln other words, the pole pieces may be passed through the effective magnetic eld or fields in one direction and then the direction of passage may be reversed to cause the induced pole pieces to pass through the effective magnetic field or fields in the opposite direction.

The loose, unattached induced pole pieces are packed into a container and are retained therein by a foraminous member forming the container bottom. Another foraminous member forms the container top; however, the induced pole pieces are not fixedly secured to the side walls or to the top or bottom members of the container and thus are permitted to move about relative to each other therewithin. As the induced pole pieces are passed between the field poles of a magnet means and through the effective magnetic field produced thereby, the induced pole pieces will move about with respect to each other within the confines of the container. The magnitudes of the displacement and force of such movement have been found to be dependent upon the strength of the magnetic field through which the pieces are passed. Although all of the factors which cause this movement to occur may not be known presently, it is believed to be the result of the interaction of the magnetic field with the macroscopic magnetic properties of the individual induced pole pieces. Such properties derive from the individual orientation of the metallic crystalline structure of each of the induced pole pieces, and the orientation of the individual magnetic fields which emanate from the pieces upon the inductive magnetization thereof. Experience has shown that movement of the induced pole pieces relative to each other will occur each time the pieces are passed through an effective magnetic field.

The movement of the induced pole pieces produces several extremely beneficial results which particularly contribute to the advantageous operation of the magnetic separator of the present invention. `Individual induced pole piece movement tends to produce a self-cleaning action. Thus, the natural propensity for sedimentary materials or gangue to accumulate on the surfaces of the induced -pole pieces which might tend to clog or impair the fiow of material through the magnetic separator is reduced.

More importantly, measurements have shown that the strength of an effective magnetic field will be maximized when the induced pole pieces move about and orient themselves under the infiuence of the linx patterns of the field. This phenomenon is one of the resultants attributable to the factors previously mentioned which are believed to cause the induced pole pieces to shift and move about within the container. It has been observed that as the induced pole pieces pass into an effective magnetic field and the various magnetic parameters interact to cause the pieces to shift and move about within the container, the strength of the magnetic field will attain a maximum value and the fiux lines will converge at certain points on the surface of each induced pole piece. This convergence occurs principally at the sharp edges of induced -pole pieces having a plurality of surface discontinuities, such as helical rods and cubes. Flux line convergence also occurs at specific regions on the surfaces of smoothly configured induced pole pieces, such as spheres. These surface points of flux line convergence provide optimum points for attracting magnetically susceptible particles present in the feed materials.

, pieces are disposed as the container enters the gap between the field poles of the magnet means. The passage of the feed material downwardly through the interstices between the induced pole pieces will be affected bya plurality of independently variable parameters, including Vthe strength of the magnetic field, the size, shape and cornposition of the induced pole pieces, the rate at which the feed material is introduced into the container, the speed at which the container is passed through the magnetic field and the size of the openings through the forarninous members of the container. As will be apparent, the physical phenomena associated with these numerous parameters will subject the feed material to a plurality of complex hydrodynamic and magnetic forces. Passage ofthe nonmagnetically susceptible material through the container will be affected by all of the hydrodynamic forces; Whereas, passage of the magnetically susceptible material will be affected by all of the forces, both of a hydrodynamic and magnetic character. The conglomerate effect of the hydrodynamic forces on the nonmagnetically susceptible particulate material results in the continuous movement of substantially all of this material with respect Ato the induced pole pieces during the entirety of the passage thereof through the container. Similarly, the conglomerate effect of thehydrodynamic and magnetic forces von the magnetically susceptible particulate material results in the continuous movement of a greater or lesser portion of this material` with respect to the induced pole pieces during the entirety of the passage thereof through the containenThis continual` motion mode of passage, experienced by substantially all of the nonmagnetically susceptible material, may be functionally characterized as to this material as a magnetically unin-fluenced, continuously dynamic passage. The greater or lesser portion of the magnetically susceptible material which is subjected to the continual motion mode of` passage will not be re* tained statically on the surface of any one of the induced pole pieces, although the individual induced magnetic vfields emanating therefrom obviously will affect the direction and velocity of such material as it passes between the pieces. This mode of passage with respect to the mag- `netically susceptible material may be functionally characterizedas a magnetically influenced, continuously dynamic passage. The principal difference between the characteristics of the passage through the container, of the nonmagnetically susceptible material and the magnetically susceptible material under conditions wherein each of the materials is subjected to forces causing continuous motion `thereof with respect to the induced pole pieces resides in the dissimilar average vertical velocity of each of .the

materials through the container, due primarily to the retarding or deterrent effect of the magnetic activity on the passageof the magnetically susceptible material. Another portion of the magnetically susceptible material, which does not undergo `magnetically influenced, continuously dynamic passage through thelcontainer, will be attracted to and statically retained intermittently on the surfaces ,of the individualwinductively magnetized` induced pole pieces, principally in the regions of flux line convergence thereon. Each of the particles passing in thismode will be statically retained on the surface of each of a plurality of 1 induced pole pieces for a perceptible interval of time,

each particle of the material thus `passing downwardly -`activity will pass through the foraminous bottom of the with intermittent, as distinguished from continuous, rno-A tion with respect to the pole pieces. This mode of passage of themagnetically susceptible material may be functionallycharacterized as magnetically influenced,`inter mittently dynamic. It will be `evident that the average vertical velocity of the portion of the magnetically sus- `ceptible material which `passes through the container in this mode will be less than that portion of such material which passes `in the magnetically influenced, continuously l dynamic mode due to the intermittent static retention of ular induced pole piece passes without the effective magnetic field, the particles statically retained thereon will be released and will pass downwardly through the container under the influence of the hydrodynamic forces acting therewithin. This mode of passage may be functionally characterized as magnetically influenced, intermittently static. The average vertical velocity of the portion of the magnetically susceptible material which passes downwardly through the container in this mode Will be less than the average vertical velocity of the material which passes in either of the magnetically influenced, continuously dynamic or intermittently dynamic modes due to the relatively long period during which the material particles are statically detained.

From the foregoing description, it will be apparent that trolled by appropriately varying one or more of the previously mentioned `parameters which affect the passage of materials through the container. Such parameters may be controlled so that a desired proportion of the magnetically susceptible material willy pass through the container in either of the magnetically influenced, continuously dynamic, intermittently dynamic or intermittently static modes. The nonmagnetically susceptible material, which passes through the container in the magnetically uninfluenced, continuously dynamic mode, largely will` pass through the foraminous bottom of the container before `the container passes out of the effective magnetic field;

this material, being unaffected by the magnetic activity, experiences the greatest downward average vertical velocity. The magnetically susceptible material largely will be deterred in the container, passing therethrough in either of the magnetically influenced, continuously dynamic, intermittently dynamic or intermittently static modes, until the container and the induced pole pieces have passed out of the magnetic field. The effect of the magnetic activity on such material being to lower the average vertical velocity thereof as it passes through the container. After the induced pole pieces have passed out of the magnetic field, the pieces will become substantially inactive magnetically, and the magnetically susceptible material being no longer subjected to the deterrent influenceV of magnetic container. Preferably, the removal of the nonmagnetically susceptible material, which occurs Vwithin the effective magnetic field, will be accelerated by a fluid wash which may be introduced into the top of thecontainer as the container is between the field poles` of the `magnet means. Similarly, the removal ofthe magnetically susceptible material, which occurs without theeffective magnetic field, preferably will be accelerated by a fluid wash also `which may be introduced into the top of the container after the container has passed from between the field poles of the magnet means. These fluid washes need not be highly pressurized since the individual movement of the induced an effective magnetic field results in a similarly reoccurring variance of the size of the interstices between the individual pieces and facilitates the passage of the particulate material therebetween and through the container. Collection means such as launders are positioned appropriately below the container for receiving the separated nonmagnetically susceptible and magnetically susceptible fractions of the feed material upon the independent exit of the fractions through the foraminous container bottom.

The ushing uid employed for the fluid washes may be liquid or gaseous, or a suitable mixture or liquid and gas. Water and/or air constitute the preferred flushing fiuids.

With respect to the hydraulic action of the various feed and iiushing fluids, it has been found that the efiiciency of the separation process may be further enhanced by coating the surfaces of the induced pole pieces with a lil-m of a nonwettable hydrophobic substance such as polytetrafluoroethylene, available commercially as Teflon, a trademark of E. I. du Pont de Nemours & Co., Inc., and modified polyvinylchloride resins, available commercially as Tygon, a trademark of U.S. Stoneware Co. By rendering the surfaces of the induced pole pieces nonwettable, the entrapment of small particles on the surfaces of the induced pole pieces by the feed and flushing iiuids due t-o fluid adhesion is minimized. In addition, the nonwettable induced pole piece surface coating substantially reduces corrosion of the pieces to thus maximize the useful operating life of the pieces. The nonwettable substance, however, does not affect the magnetic properties of the pieces.

In accordance with one embodiment of the invention, the induced pole pieces, after the magnetically susceptible material has been removed from the proximity thereof and collected, are passed through a degaussing unit in order to remove any residual magnetism in the induced pole pieces and to facilitate the removal of any magnetically susceptible materials which have not been removed from the container by the fluid wash following exit of the induced pole pieces from the effective magnetic field. Such degaussing equipment may be chosen from any degaussing equipment known in the art and preferably will comprise coils disposed on opposite sides of the container in which the induced pole pieces are disposed which will be powered by an alternating current -of sufiicient strength to effect any degaussing necessary.

Alternatively, in magnetic separators employing a plurality of magnet means, a degaussing effect may be achieved by reversing the polarity of each successive magnet means. With such an arrangement, an area of polarity reversal between each successive magnet means will occur which is substantially free of any magnetic activity. Any magnetically susceptible materials which previously have not been removed from the container may be removed quite easily in such an area, either under the intiuence of gravity or with the assistance of a fluid wash. By reversing the lpolarity of each successive magnet means in a plural magnet means separator, the requirement for a degaussing unit may be obviated, further reducing the cost of the apparatus.

The magnetic separator of the present invention is a device of flexible usage; one embodiment thereof having particular utility for separating a desired nonmagnetically susceptible material from a feed having highly magnetically susceptible, weakly magnetically susceptible and the desired nonmagnetically susceptible materials intermingled therein. A problem that has often precluded the commercial feasibility of such a separation is the entrapment of small particles of the nonmagnetically susceptible material by the highly magnetically susceptible material, thus preventing the separate recovery ofthe valuable nonmagnetically susceptible material. This problem is largely alleviated by one embodiment of the present invention. In this embodiment, the container which retains the loose, unattached, individually movable induced pole pieces is provided with higher side walls. Between the upper portions of the side walls a plurality of the induced pole pieces are positioned in such a manner as to be held continuously above the gap between the field poles of a magnet means through which the container is passed. The induced pole pieces positioned above the gap are not subjected to the intense magnetic field produced therein and thus are inductively magnetized to a lesser extent than the induced pole pieces which pass through the gap.

In the operation of this embodiment, as the container and induced pole pieces pass into an effective magnetic field and the feed materials are introduced into the top of the container, the highly magnetically susceptible material in the feed will be deterred by the slightly magnetized induced pole pieces, such material passing through the interstices between the pieces in the magnetically influenced, continuously dynamic, intermittently dynamic and intermittently static modes. The weakly magnetically susceptible and nonmagnetically susceptible materials will pass through the upper portion of the container and past the slightly magnetized induced pole pieces in essentially the magnetically uninuenced, continuously dynamic mode, these materials thus experiencing a greater downward vertical velocity through this portion of the container than the highly magnetically susceptible material. The weakly magnetically susceptible and nonmagnetically susceptible materials will then pass into proximity with the highly magnetized induced pole pieces within the gap between the field poles. At this point, the major portion of the weakly magnetically susceptible materials will be deterred by the highly magnetized induced pole pieces, passing therebetween in the magnetically infiuenced, continuously dynamic, intermittently dynamic and intermittently static modes; the average vertical velocity of this material thus being reduced with respect to the average vertical velocity of the nonmagnetically susceptible material. The nonmagnetically susceptible material which is unaffected by the magnetic activity, passes downwardly between the highly magnetized induced pole pieces in the magnetically uninliuenced, continuously dynamic mode and thereafter through the foraminous container bottom and into a launder or other collecting means positioned below the container.

As in the previously described separation process, the nonmagnetically susceptible material is removed from the container while the container is within the effective magnetic field, and the magnetically susceptible materials, both of a high and weak magnetic susceptibility, are removed from the container without the effective magnetic field. Also as in the previously described operation, this separation process may be regulated by controlling the numerous parameters which affect the passage of materials through the container. The significance of this profess resides in the marked reduction of entrapment of the nonmagnetically susceptible material by the highly magnetically susceptible material which is realized as a result of the initial deterrence of the latter material by the slightly magnetized induced pole pieces.

In some mineral separation process, it has been found that if greater than .04% of a valuable nonmagnetically sus-ceptible material is entrapped and lost with the magnetically susceptible materials, the separation process is not economically feasible. By utilizing a separator of the present invention having raised container side walls which position a portion of the induced pole pieces above the gap between the field poles, the separation of a desired nonmagnetically susceptible material can be accomplished in an economically attractive manner.

The container in which the induced pole pieces are disposed may be modied in another manner. The side walls of the container may be extended downwardly, terminating at a point below the gap between the field poles of a magnet means so that a plurality of the induced pole pieces will be positioned continuously below the gap as the container passes therethrough. In this embodiment,

the highly permeable induced have a configuration that is either similar toor dissimilar from the induced pole pieces. Also, the size of such bodies vmay be` substantially the same asor'different from that of the induced pole pieces. The selection ofnonmagnetically susceptible bodies of a particular composition, shape `and "size, ismade on the basis of the effect of such bodies on `the hydrodynamic forces which are imposed on the materials passing through the container. By placing non- -magneticallysusceptible bodies ofan appropriate composition, `shape andsizein the lower portion of a` con- "tainer which extends below the gap between the eld ipoles," the hydrodynamic forces imposed on the feedmaf terialsmaybe regulated and the average downward vertical' velocity ofthe materials through vthe container may AMbe controlled. *Regulation of the hydrodynamic forces affects the passageof all ofthe materials through the containerto a greater or lesser extent; specifically all of ythe"materialsvvhich pass through` the container in each Yof the magnetically uninfiuenced, continuously dynamic; magnetically influenced, continuously dynamic;

magnetically influenced, intermittentlydynamic andmagnetically infiuenced, intermittently static modes.

Havinggenerally described the present invention and various of the modifications and embodiments thereof,

more detailed illustrations are `provided with reference to the following drawings in which:

FIG. 1 is a plan viewof a two-magnet, rotary separator in accordance with the invention;

FIG. 2 is a sectional elevational View net, rotary separator of FIG. 1, taken FIG. 1;

FIG. 3 is a side view of the two-magnet, rotary separator ofFIG. 1 showing, the drive motor in position and the operating parts suitably encased;

FIG. 4 is a fragmentary plan view showing a plurality of induced pole pieces disposed within a rotatable annular container;

FIG. 5 is an elevational view of ahelically configured induced pole piece;

FIG. 6 is a diagrammatic rator shown in FIGS. 1-3 of introduction of the feed and'fluid `washes and the removal of` the separated materials in accordance with the invention;

FIG/7 is a schematic plan view of a ten-magnet, rotary `separator in accordancewith the invention;

FIG.`8 `is a plan viewof a three-magnet, in-line sepa rator in accordance withthe invention;

FIG. 9 is a side View of the three-magnet, in-line sepa- `rator"shown in FIG.` 8;

AFIG.l 10 is an enlarged fragmentary plan view showing of the `two-magon line 2-2 of plan view of the rotary sepaa plurality of helically configured induced pole pieces disposed within an annular container;

FIG. 11 is a vertical sectional elevational view showi ing a plurality of spherically configured induced `pole ypieces disposed within an annular container; FIG. 12is a diagrammatic `plane view of a two-magnet rotary separator showing the polarity arrangement of the magnet means in one embodiment of the invention; and

FIG. 13 is an enlarged fragmentary sectional view of a portion `of themagnetic `separator ofthe invention ac- `cordingto one modification thereof; all in accordance with various embodiments of the prevent invention.

Itherein a nonmagnetic support frame 1 Referring particularly to FIGS. 1-3, there is shown which :supports two magnet means,electromagnet assembliesZ. Each magnet assembly 2 comprises `a pair of magnet cores 3, 3 bolted to an insert 4 adjacent support frame 1.` Field #poles 5 and 6 are secured to the top` ends of magnet cores `.3 3l

i gap 7.' Core 4windingsS, 8

respectively, and define therebetween anoperating further showing the sequence are wound around cores 3, 3';

Cil

v annular foraminous screen 26 10 sixty-six thousand ampere turns being required to produce a field having a strength of about 22,800 gauss. The joints between cores 3, 3', insert 4 andiield poles 5 and 6 are ground to a smooth finish to provide amaximum ilux' path. All edges of the complete magnet assemblies 2 are rounded to prevent leakage of stray flux. Field poles `5 and are tapered toward operating gap'7 therebetween,

`black inside and out to provide maximum cooling.

A center structural support member 11 supports a drive mechanism 12. Preferably support member 11 isconstructed of `a nonmagnetically` susceptiblematerial such as a Series 300 stainless steel. Supportmember` 11 is secured to `field poles 5 by supportingbolts 13. A nonmagnetically susceptible head member 14, preferably an aluminum casting, is rotatably mounted on a stationary stub shaft 15 `by means of a sleeve bearing16 anda thrust bearing`17. A motor drivel mechanism 18 is mounted on and bolted to supporting head member 14`for rotatably driving the head member. Afiixed to head member 14 and rotatable therewith isa hollow annular container`19 formed by concentric annular rings 20 and 21. Annular container 19 is interiorly supported by supporting members, subsequently described.

Motor drive mechanism 18 rpreferably comprises va gear-head `motor 23:` provided with conventional slip rings (not shown) foreonnecting the motor to an external source of electrical power; The torque generated by motor 23 reacts aganst'a stationary hollow shaft 24 affixed to shaft 15, and the motor rotates with support'member 14. Alternatively, the motor drive mechanism may comprise a stationary mounted motor drivingly connected to head member 14 by a ring gear, the ring gear being affixed to the headmember and being engaged by a pinion gear rotatably driven by the motor.

Annular container 19 retains therein a plurality of loose, unattached helical induced pole pieces 25. Helical induced pole pieceslZS` are preferably fabiricatedfrom a magnetically soft, low carbon steel and are positioned vertically within container 19.`The induced pole Ipieces are retained within container 19 by an annular foraminous screen l22 forming the container bottom. Another forms the top'iof container 19. Interior'supporting members 27, which are `formed by silver soldering togethera` plurality of helical induced pole pieces 25, are solderedto annular rings 20 and 21. Supporting members 27 divide annular container 19 `into a plurality of compartments 28', and provide `internal support for annular rings 20` and21, to thus ensure the structural rigidity of container V19.

Asbestiseen in FIG. 10, helical induced pole pieces 25 are retained withincompartments 28 byvscreen 22 at the bottom` of container 19. Movement of; the induced pole pieces also is limitedl by the container side walls, annular rings 20 and 21, and the container top, annular foraminous screen 26, but the pieces..arenotlsecured iixedly to any `portion of the container. Inducedpole pieces 25 thusare free to shift and move about individually relative to each and the individual macroscopic magnetic properties of the induced pole pieces, as previouslyidescribed.

Alternativey, instead of the helical induced pole pieces Z shown in FIGS. 5 and l0, a plurality of loose, unattached spherical induced pole pieces 70 may be placed into container 19. Spherical induced pole pieces 70 will shift and move about with respect to each other within container 19 in a manner similar to the magnetically induced movement of helical induced pole pieces 25, as pieces 70 pass through the effective magnetic fields pro duced between field poles 5 and 6.

The induced pole pieces, whether of helical, spherical or of other configuration, will orient themselves within container 19 in such a manner as to maximize the field strength of the effective magnetic elds between field poles 5 and 6. The presence of the -pole pieces in the effective magnetic fields also results in convergence of the flux lines at specific points or regions on the surfaces of the pieces. It is to be understood that these desirable -resultants occur to a greater or lesser extent with induced pole pieces of vairous shapes, and that the particular description of helically shaped and spherically shaped induced pole pieces is not intended to be limiting, but as exemplary of various of the many induced pole pieces configurations which may be utilized.

Feed nozzles 28, from which the feed material is directed, are disposed above container 19 adjacent one end of gaps 7 between field poles 5 and 6, as best seen in FIGS. 1 and 3. Nozzles 29 for introducing washing fluid are disposed above container 19 in substantially the center of gaps 7 between fleld poles 5 and 6. Nozzles 30 for washing fiuid are disposed -above container 19 adjacent field poles S and 6 at the opposite end of gaps 7 from feed nozzles 28.

A degaussing unit 31, comprising a magnetic yoke 32 powered by alternating current, is situated at one position along the circular path traversed by container 19 for neutralizing any residual magnetic activity within the container, A nozzle 33 for washing fluid is disposed over container 19 at a point adjacent degaussing unit 31; the washing fiuid assisting the removal of any residual magnetic material released from the container incident to the demagnetizing influence of unit 31.

Launders 34 and 35 are disposed beneath -container 19 for receiving, respectively, the nonmagnetically susceptible and magnetically susceptible materials separated. As will be apparent from FIG. 6, the construction of the two-magnet separator shown in FIGS. 1-3 includes two diametrically opposed nonmagnetically susceptible material collection launders 34 and two `diametrically opposed magnetically susceptible material collection launders 35. Launders 34 are equipped with outlets 36, While launders 3S are equipped with outlets 37.

The operation of the magnetic separator described above in conjunction with FIGS. 1-3 will now be characterized. Initially, motor 23 is started, causing container 19 to rotate about the axis of shaft 15. Induced pole pieces 25, retained within container 19, thus are successively moved between field poles 5 and 6 of magnet assemblies 2 which are disposed at opposite sides of the separator. Power is supplied to magnet assemblies 2 for generating an effective magnetic field between field poles 5 and 6 of each of the electromagnets. As the loose, unattached induced pole pieces successively enter the effective magnetic fields generated between field poles 5 and 6, the pieces shift and move about with respect to each other within container 19 assuming positions which produce an optimum magnetic configuration as previously described. A slurry of the material to be separated is introduced through feed delivery nozzles 28. Fluid wash is introduced through nozzles 29, 30, and 33. The nonmagnetically susceptible material, unaffected by the magnetic fields, falls through screen 26, the interstices between induced pole pieces and screen 22 in the magnetically uninfluenced, continuously dynamic mode of passage. The magnetically susceptible material passes downwardly through container 19 in the magnetically infiuenced, continuously dynamic, intermittently dynamic and intermittently static modes. Removal of the nonmagnetically susceptible material from container 19 occurs within the effective magnetic fields produced in gaps 7 and is assisted by the fluid washes from nozzles 29. As induced pole pieces 25 leave operating gaps 7 the pole pieces pass without the effective magnetic fields, and the magnetically susceptible particles are there removed from container 19 with the assistance of fluid washes from nozzles 30. Any material having a tendency to adhere to the surfaces of induced pole pieces 25, which might tend to clog or impair the flow of feed through container 19, largely will be removed from the pole pieces incident to the scraping and rubbing of the pieces against each other which results upon the individual movement of the pieces as they successively enter operating gaps 7. The nonmagnetically susceptible material removed in the magnetic fields is collected in launders 34 and removed through outlets 36. The magnetically susceptible material is collected in launders 35 and removed through outlets 37. As container 19 rotates, induced pole pieces 25 pass through the alternating field of degaussing unit 31. Any residual magnetically susceptible materials remaining in container 19 are released at this point and are removed therefrom with the assistance of the uid wash Ifrom nozzle 33, such materials being collected in one of the launders 35.

The separator shown in FIGS. 1-3, constructed to the dimensions and utilizing the power shown in the table below, was employed to separate molybdenum ore containing 0.05% by weight of molybdenum oxide. The capacity of the separator was found to be in excess of 4,000 pounds per hour; the yield was 93.7% of the recoverable molybdenum.

Cross-sectional dimensions In one modification, magnet cores 3, 3' and field poles 5 and 6 are arranged in a manner which obviates the necessity for incorporating a separate degaussing unit. In this modification, the magnet assemblies are positioned with the polarity of each successive magnet assembly arranged oppositely to the polarity of the preceding magnet assembly. This construction is shown diagrammatically in FIG. 12, wherein the polarities of magnet assemblies and 82 are shown by the letters N and S, representing the North and South magnetic poles, respectively. The N-S poles of magnet assembly 82 are reversed with respect to the N-S polarity of magnet assembly 80. The effective magnetic fields generated by magnet assemblies 80 and 82 will achieve maximum magnitude in the regions designated as points A and B, respectively. However, due to the reversed polarity of magnet assemblies 80 and 82, the magnetic field strength in the regions designated as points C and D will be of substantially zero magnitude. Any residual magnetically susceptible materials remaining in the container are removed therefrom as the container passes through the regions of points C and D. (I-f desired, a liuid wash may be introduced into the top of the container adjacent points C and D to assist in the removal of any such materials. n

In FIG. 7, a ten-magnet, rotary separator is shown. Except for the increased number of magnet means, the separator of FIG. 7 is constructed and functions in the 13 same manner as the separator described in conjunction with FIGS. 1 3.

Specifically, an annular container 40 is rotatably mounted to pass between field poles 41 and 42 of ten magnets 43. Container 40 is filled with loose, unattached induced pole pieces, such as helical induced pole pieces or spherical induced pole pieces 70, made of a highly permeable soft magnetic material. Feed material such as a slurry of molybdenum ore is introduced through feed nozzles 44. The nonmagnetically susceptible material passes through container in the magnetically uninfluenced, continuously dynamic mode with the assistance of fiuid washes provided by wash nozzles 45. As container 40 is rotated, the magnetically susceptible material, which passes through container 40 in the magnetically inuenced, continuously dynamic, intermittently dynamic and intermittently static modes, is moved out of the effective magnetic elds produced by magnets 43 and removed from the container with the assistance of uid washes provided by wash nozzles 46. The separated materials are suitably collected in launders (not shown). A degaussing unit (not shown) may be employed as in the separator of FIGS. 1-3, or preferably the polarity of each magnet 43 is reversed with respect to the polarity of the adjacent magnets, in the manner described in conjunction with FIG. 12.

An in-line separator is shown in FIGS. 8 and 9 having a foraminous-bottomed box reciprocally mounted to pass between the field poles 51 and 52 of a plurality of electromagnets 53. Reciprocal motion is imparted to box 50 by an eccentric drive assembly 54. A plurality of loose, unattached induced pole pieces, such as helical rods, cubes or spheres of a highly permeable soft magnetic material, are retained within box 50.

Feed nozzles 55 and 56 are located above box 50 adjacent the opposite outer edges of field poles 51 and 52. The feed material is directed alternately to nozzles 55 and 56 through a feed line 57 and two-way valves 58.

Fluid wash nozzles 59 are disposed above box 50 at a point intermediate feed nozzles 55 and 56. Additional fluid wash nozzles 60 are disposed above box 50 outside the gaps between field poles 51 and 52, and are spaced from feed nozzles 55. A further group of fluid Wash nozzles 61 are disposed above box 50 outside the gaps be- `tween field poles 51 and 52, and are spaced from feed nozzles 56. Wash nozzles 60 and 61 are connected through valves 62 and 63, respectively, to a fiuid wash delivery line 64.

Launders 65, for collection of the magnetically susceptible material separated, are disposed below box 50 and beneath wash nozzles 60 and 61. Launders 65 empty into a header 66 from which the magnetically susceptible material is withdrawn from the separator. Launders 67, for collection of the nonmagnetically susceptible material separated,l are disposed below box 50 and beneath wash nozzles 59. Launders 67 empty into a header 68 from which the nonmagnetically susceptible material is Withdrawn from the separator.

The separator shown in FIGS. 8 and 9 operates in the following manner. Initially, drive mechanism 54 is actuated which, for example,`moves box 50 to the right. Feed material is introduced into the top of box 50 through valves 58 and feed nozzles 55, valves 58 preventing delivery of feed material to feed nozzles 56. As the feed material moves into the effective magnetic fields between field poles 51 and 52, and therein into proximity with the induced pole pieces retained in box 50 the nonmagnetically susceptible material passes through box 50 in the magnetically uninfiuenced, continuously dynamic mode while the magnetically susceptible material passes throughbox 50 in the magnetically influenced, con tinuously dynamic, intermittently dynamic and intermittently static modes. The nonmagnetically susceptible material isremoved from box 50 with the assistance of fluid Washes from nozzles 59 and is received Vin launders 67 for removal from the separator through header `68. `As box 50 approaches the limit of travel, valves 58 shut olf the flow of feed material through feed nozzles 55 while valves 63 are actuated to introduce uid washes to the top of box 50 through wash nozzles 61. Magnetically susceptible material, now outside the effective magnetic fields of field poles 51 and 52, is removed from box 50 into launders 65 with the assistance of fluid washes from nozzles 61 and is removed from the separator through header 66.

At this point, the direction of travel of box 50 is reversed. Valves 58 are now actuated to direct the flow of feed material through feed nozzles 56. Valves 63 are actuated to shut off the flow of wash fluid through nozzles 61, and valves 62 are actuated to initiate the iiow of wash fluid through nozzles 60.

The process above described is now repeated as box 50 travels to the left between field poles 51 and 52. Nonmagnetically susceptible material is removed from box 50 within the magnetic fields produced between field poles 51 and 52 with the assistance of fiuid washes introduced through nozzles 59. Magnetically susceptible material is removed from box 50 Without the effective magnetic fields with the assistance of fluid washes from nozzles 60. Nonmagnetically susceptible and magnetically susceptible materials again are collected in launders 67 and 65, respectively, and removed from the separator as before.

Accordingly, it will be seen that the in-line separator shown in FIGS. 8 and 9 operates continuously, the separation process necessitating only the actuation of a few valves to effect the flow of feed material and fluid washes through the proper nozzles as the direction of travel of box 50 changes. p

In either a rotary or an in-line separator, it is possible to employ a single magnet means or as many magnet means as may be desirable or practical in a particular operation. Also, as mentioned previously, it is usually desirable to coat the induced pole pieces with a nonwettable substance to minimize liquid adhesion entrapment of small particles on the surfaces of the pieces, .and to extend the operating life of the pieces.

The magnetic separator construction shown in FIG. 13 is an embodiment which is particularly adapted for separating a desired nonmagnetically susceptible material from a feed comprising a mixture of highly magnetically susceptible, weakly magnetically susceptible and the desired nonmagnetically susceptible materials. An example of such a feed is a natural mixture of highly magnetically susceptible magnetite, relatively weakly magnetically susceptible ilmenite, and rutile. In this mixture, the rutile, a natural ore of titanium, is a material of particular economic significance and is of an extremely low magnetic susceptibility.

The separator construction shown in FIG. 13 is similar in many respects to the magnetic separators previously described in conjunction with FIGS. 13 and FIGS. 8 and 9. Elements which have been described previously, therefore, are identified in FIG. 13 by like reference numerals. This embodiment includes a container having opposed side walls 92 and 94 which extend above gap 7 between magnet field poles 5 and 6. Side walls 92 and 94 may be configured as concentric annular rings similar to annular rings 20 and 21 for use in a rotary separator, or may be linearly configured as components of a rectangular container, such as box 50, for use in an in-line separator. As is shown in FIG. 13, side walls 92 and 94 extend an appreciable distance above gap 7. Foraminous screen 22 extends between the lower ends of side walls 92 and 94 and defines the bottom of container 90. A plurality of induced pole pieces, such as spherical inducedl pole pieces 70, are placed into container 90 on top of foraminous screen 22. A portion of the induced pole pieces will be positioned at all times above gap 7 in the upper portion of container 90, The remainder of the induced pole pieces, which are positioned in the lower portion of container 90, will be carried by the container through gap 7. Foraminous screen 26 extends between the upper portions i of side walls 92 and 94 to further confine the induced pole pieces within container 90.

The operation of this embodiment is similar in many respects to the operation of the rotary separator shown in FIGS. 1-3, and the in-line separator shown in FIGS. 8 and 9, both of which have been described previously. However, there are some differences between the separation process performed by the separator shown in FIG. 13 and that effected by the magnetic separators previously described due to the extended height of container 90.

In particular, the induced pole pieces retained in the upper portion of container 90 will not be subjected to the intense magnetic field in gap 7 and will not 4become as highly magnetized as the induced pole pieces which are retained in the lower portion of container 90, and which do pass directly between field poles 5 and 6. Since the induced pole pieces positioned in the upper portion of container 90 are magnetized, only weakly, the weakly magnetically susceptible material in the feed will pass through the interstices between these pole pieces in essentially the magnetically uninfluenced, continuously dynamic mode, similar to the mode of passage of the nonmagnetically susceptible material between the pole pieces which are both highly and weakly magnetized. The highly magnetically susceptible material in the feed, such as magnetite, however, will be deterred in the upper portion of container 90 by the weakly magnetized induced pole pieces, passing therethrough in the magnetically influenced, continuously dynamic, intermittently dynamic and intermittently static modes. The nonmagnetically susceptible and weakly magnetically susceptible materials will pass down through container 90 and into proximity with the highly magnetized induced pole pieces positioned in the lower portion thereof. These materials will there be separated in the manner described previously in connection with the operation of the separator shown in FIGS. l3; the weakly magnetically susceptible material passing downwardly in the magnetically influenced, continuously dynamic, intermittently dynamic and intermittently static modes with a lower average vertical velocity than the nonmagnetically susceptible material which experiences the magnetically uninfiuenced, continuously dynamic mode of passage.

By first separating the highly magnetically susceptible material in a zone of weak magnetic activity, entrapment of the nonmagnetically susceptible and weakly magnetically susceptible -materials by the material of high magnetic susceptibility will be minimized significantly. As the weakly magnetically susceptible material is deterred in the lower portion of container 90, the nonmagnetically susceptible material passes through foraminous screen 22 at the bottom of the container, substantially uncontaminated by any of the magnetically susceptible materials. The valuable nonmagnetically susceptible material thus is separated from the feed and separatedly collected as the induced pole pieces pass through the effective magnetic field produced between poles 5 and 6. The highly magnetically susceptible and weakly magnetically susceptible materials are removed from container 90 after induced pole pieces 70 have passed without the effective magnetic field; the deterrent effect of the magnetic forces on the passage of such materials having terminated at this point due to the absence of magnetic activity. The re* moval of the nonmagnetically susceptible as well as the magnetically susceptible materials may be facilitated by introducing fluid washes into the container in a manner similar to that described above in conjunction with the rotary magnetic separator shown in FIGS. 1-3 and the in-line separator shown in FIGS. 8 and 9.

The magnetic separator construction shown in FIG. 13 permits the separation of valuable nonmagnetically susceptible material in a single apparatus without the occurrence of significant losses of such material. The feed need not be separately treated first in a scalping machine, for removing the highly magnetically susceptible material prior to the separation of the nonmagnetically susceptible material from the weakly magnetically susceptible material, as has been the common practice heretofore. All of the necessary separating functions are accomplished in a single apparatus, and in a manner which minimizes entrapment of the valuable nonmagnetically susceptible material by the highly magnetically susceptible material. As will be evident, this construction provides an economically attractive method for separating valuable nonmagnetically susceptible materials.

In addition, the embodiment of the magnetic separator shown in FIG. 13 has been found to give excellent results in the separation of a desired weakly magnetically susceptible material from a nonmagnetically susceptible waste material. The operation of the apparatus for effecting this separation process is identical to the operational methods described previously in conjunction with the rotary separator shown in FIGS. 1 3 and the in-line separator shown in FIGS. 8 and 9. Due to the increased number of induced pole pieces, specifically the pieces carried in the upper portion of container 90, the magnetic and hydrodynamic forces may be more accurately controlled, thus allowing increased accuracy to be achieved in the regulation of the average vertical velocities of the materials through the container.

A separator constructed and operated in accordance with the parameters shown in the following table was utilized to separate ilmenite, a weakly magnetically susceptible ore of titanium, from a slurry containing a solid materials mixture comprising silica and 25% ilmenite by weight. The magnetically susceptible fraction recovered contained 98.9% ilmenite which consisted of 85.1% of the total ilmenite present in the feed.

Cross-sectional dimension of magnet cores 5.0 in. diameter. Cross-sectional dimensions of field poles 3.0 in. x 4.0 in. Width of gap between field poles 2.5 in. Average number of spherical induced pole pieces 300. Height of container 8 in. Strength of each field 20,000 gauss.

A further embodiment of the invention provides another means for accurately controlling the hydrodynamic forces imposed on the particulate materials which pass through the container. This embodiment employs an induced pole piece container having side walls that extend downwardly below the gap between the field poles. This structure is similar to that shown in FIG. 13 except that the container extends below instead of above the gap. The lower portion of such a container may be filled with highly permeable soft magnetic induced pole pieces or preferably with nonmagnetically susceptible bodies, composed, for example, of a ceramic or plastic material, or of a nonmagnetically susceptible metal such as an alloy of aluminum. Alternatively, the lower portion of the container may be filled with a mixture of induced pole pieces and nonmagnetically susceptible bodies. The bodies may be of the same lshape and size as the induced pole pieces or of a different size and/ or shape as required for obtaining the desired hydrodynamic forces.

The marked increase in efiiciency which may =be achieved in some separation processes by utilizing a container with side wallsl which extend below the operating gap of a magnet means is evidenced by the following example. An induced pole piece container was extended four inches below the gap between the field poles of an electromagnet and this portion of the container was filled with the same 3%; inch diameter spherical induced pole pieces as were used for filling the upper portion of the container. A feed comprising a slurry of weakly magnetically susceptible iron ore admixed with nonmagnetically susceptible particulate materials was passed through the container, resulting in the separation of 74% by weight of the recoverable iron from the other particulate materials present in the feed. The test was performed again employing the same feed slurry and the same apparatus except that the bottom four inch portion of the container was filled with spherical ceramic beads having a diameter of three millimeters. The relatively small, nonmagnetically susceptible beads reduced the fiow rate of the feed slurry through the container from 0.993 liter/second to 0.311 liter/second with the resulting separation of 90% by weight of the recoverable iron present in the feed. Ity

will be seen from this example that by appropriately regulating the parameters which affect the hydrodynamic forces generated within the container, the efficiency of the separation process may be increased significantly for some materials.

Also, for the separation of particular materials it may be advantageous to intermix nonmagnetically susceptible bodies, such as the ceramic `beads mentioned in the previous example, with the induced pole pieces throughout the entire height of the container. This arrangement will reduce the flux line concentration which results upon passage of the pole pieces through an effective magnetic field to thus decrease the magnetic forces imposed on the materials passing through the container while maintaining the desired hydrodynamic forces throughout the separating zone. A container having disposed therein a mixture of induced polerpieces and nonmagnetically susceptible bodies may be employed in any of the previously described separator embodiments, including thosev shown in FIGS. l-3, FIGS. 8 and 9, and FIG. 13, as well as in separator having a container which extends below the gap between the field poles of a magnet means.

rThe separators of the invention are economical to construct and operate and are readily serviced. Due to the small number of moving parts, the separators of the invention have proven essentially trouble-free in extended operation.

Since modifications in the `equipment and methods herein disclosed will be apparent to tho-se skilled in the art, it

isV intended that the invention be limited solely by the scope of the appended claims.

What is claimed is: 1. Au apparatus for separating granular materials of differing magnetic susceptibility comprising:

at least one magnet means having oppositely disposed field poles of opposite polarity for producing an effective magnetic field therebetween;`

a pluarlity of loose, unattached induced pole pieces, said induced pole pieces being individually `means for carrying and retaining the induced pole pieces, movable relative to each other;

means for moving the induced pole pieces and the field poles relative to each other so that the induced pole pieces pass into, through and out of theefiective magnetic lfield; I

means for introducing the material .to be separated into the effective magnetic :field and therein into proximity with the induced pole pieces as the pieces pass through the field; and i means for flushing material `from proximity with the induced pole pieces after the pieces have passed out of the effective magnetic field.

2. An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 1 wherein said induced pole pieces are helically configured.

3. "An apparatus for separating Igranular materials of differing magnetic susceptibility as recited in claim 1 wherein said induced pole pieces are spherically configured.

4. An apparatus for separating -granular materials of differing magnetic susceptibility as recited in claim 1 wherein said induced pole pieces are coated with a nonwettable substance.

5. An apparatus for separating granular materials of differing magnetic susceptibility las recited in claim 1 wherein a plurality of loose, unattached nonmagnetically susceptible bodies are ntermixed with said induced pole pieces. p f

6. An apparatus for separating granular materials of differing magnetic susceptibility as recited `in claim 1 further comprising a degaussing means positioned without the effective magnetic field land adjacent the induced pole pieces for ensuring the demagnetization of the pole pieces and any of the materials to be separated remaining in proximity therewith.

7..An apparatus for separating granular materials of differing magnetic susceptibility comprising.:

at least one magnet means having oppositely disposed field poles defining a gap therebetween, said field poles being of opposite polatitypfor producing an effective magnetic field therebetween;

a movable container disposed within the gap, said container having a foraminous bottom;

a plurality of loose, unattached induced pole pieces disposed within the container and retained therein by the foraminous bottom, said pole pieces being individually movable relative to each other;

means for moving the container and the induced pole pieces disposed therein relative to the field poles so that the induced pole pieces successively pass into, through and out of the effective magnetic field;

means for introducing the material to be separated into the effective magnetic field and therein into proximity with the induced pole pieces disposed within the container as the pole pieces pass through the field; and

means for flushing material from the container and from proximity with the induced pole pieces disposed therein after the pieces have passed out of the effective magnetic field.

8. An Yapparatus for separatinggranular materials of differing magnetic susceptibility as recited in claim 7 wherein said means Vfor moving the container and the induced pole pieces retained therein relative to the field poles comprises means for reciprocating the container.

9. `An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 7 wherein said container comprises an annular member rotatably mounted to pass through the Igap defined between the `field poles of the magnet means.

10. An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 7 wherein a plurality of loose, unattached nonmagnetically susceptible bodies are ntermixed with said induced pole pieces within the container. t

11. An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 7 wherein said container` has side walls which extend above the gap defined between the field poles of the magnet means, said side walls defining therebetween a portion ofl the container which remains above the gap at all times, and wherein at least some of said plurality of induced pole pieces disposed within the container are positioned in the portion thereof which remains above the gap.

12. An` apparatus for separating granular materials of differing magnetic susceptibility as recited in claim` 11 19 wherein a plurality of loose, unattached nonmagnetically susceptible bodies are intermixed with said induced pole pieces within the container including the portion thereof which remains above the gap at all times.

13. An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 7 wherein said container has side walls which extend below the gap defined between the field poles of the magnet means, said sidewalls defining therebetween a portion of the container which remains below the gap at all times, and wherein at least some of said plurality of induced pole pieces disposed within the container are positioned in the portion thereof which remains below the gap.

14. An 'apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 13 wherein a plurality of loose, unattached nonmagnetically susceptible bodies are intermixed with said induced pole pieces Within the container including the portion thereof which remains below the gap at 'all times.

15. An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 13 wherein the portion of said container which remains below the gap at all times is filled with a plurality of loose, unattached nonmagnetically susceptible bodies.

16. An apparatus for separating granular materials of differing magnetic susceptibility comprising;

a plurality of magnet means, each of said plurality of magnet means producing an effective magnetic field between opositely disposed field poles of opposite polarity intergr'al therewith, the eld poles of each of the magnet means defining a gap therebetween;

a container mounted to pass through the gap between the field poles of each of the magnet means, said container having a foraminous bottom;

a plurality of loose,vunattached induced pole pieces disposed within the container and retained therein by the formainous bottom whereby granular material may pass through the interstices between the pole pieces and through the foraminous bottom;

means for `moving t-he container and the induced pole pieces disposed therein relative to the field poles so that the induced pole pieces successively pass into, through and out of the effective magnetic fields;

means for introducing the material to be separated into the effective magnetic fields and therein into proximity with the induced pole pieces disposed within the container as the pole pieces pass through the fields; and

means for flushing material from the container and from the proximity with the induced pole pieces diposed therein after the pieces have passed out of the effective -magnetic elds.

17. An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 16 wherein the polarity of each of the magnet means is opposite to the polarity of the adjacent magnet means.

18. An apparatus for separating granular materials of differing magnetic susceptibility comprising:

a plurality of magnet means, each of said plurality of magnet means producing an effective magnetic field Ibetween oppositely disposed field poles of opposite polarity integral therewith, the field poles of eac-l1 of the magnet means defining a gap therebetween;

a container mounted to pass through the gap between the field poles of each of the magnet means, said container having a foraminous bottom;

a plurality of loose, unattached induced pole pieces disposed Within the container and retained therein by the formainous bottom whereby granular material may pass through t-he interstices between the pole pieces 'and through the foraminous bottom;

means for moving the container and the induced pole pieces disposed therein relative to the field poles so that the induced pole pieces successively pass into, through and out of the effective magnetic fields;

means for introducing granular material into the container and into proximity with the induced pole pieces disposed therein as the container passes through the effective magnetic fields;

a first delivery means for introducing ushing fiuid into the contaner as the container passes through the effective magnetic fields;

a second delivery means for introducing iiushing fluid into the container after the container has passed without the effective magnetic fields;

a first collecting means for receiving granular material removed from the container within the effective magnetic fields; and

a second collecting means for receiving granular material removed from the container without the effective magnetic fields.

19. An apparatus for separating granular materials of differing magnetic susceptibility as recited in claim 18 wherein the polarity of each of the magnet means is opposite to the polarity of the adjacent magnet means.

20. A method for separating `granular materials of relatively low magnetic susceptibility from materials of relatively high magnetic susceptibility which comprises:

passing a mixture of the materials to be separated into an effective magnetic -field and therein into proximity with -a plurality of loose un'attached individually movable bodies, at least some of which are composed of a highly magnetically permeable material and all of which are confined within a means for carrying and retaining said bodies;

thereafter passing the mixture of materials to be separated into proximity with a plurality of loose unattac-hed individually movable, nonmagnetically susceptible bodies, all of lwhich are confined within said carrying and retaining means;

removing the material of lower magnetic susceptibility from the proximity with all of the individually movable bodies Vand from the material of higher ma-gnetic susceptibility While both materials and the highly magnetically permeable bodies are within the effective magnetic field;

separately collecting the material of lower magnetic susceptibility;

removing the material of higher magnetic susceptibility `and the highly magnetically permeable bodies from the effective magnetic iield;

removing the material of higher magnetic susceptibility from proximity with all of the individually movable bodies; and

separately collecting the material of higher magnetic susceptibility.

21. A method for separating nonmagnetically susceptible materials from .granular materials of relatively weak and relatively high magnetic susceptibility which comprises:

passing a mixture of the material to be separated into a relatively weak magnetic field and therein into proximity with a plurality of loose unattached individually movable bodies, at least some of which are composed of -a highly magnetically permeable material and all of which lare confined within a means for carrying and retaining said bodies, for separating the material of higher magnetic susceptibility from the nonmagnetically susceptible material and the material of weaker magnetic susceptibility;

thereafter passing the nonmagnetically susceptible material and the material of weaker magnetic susceptibility into a relatively strong magnetic field and therein into proximity with 'a plurality of individually movable bodies, at least some of which are composed of a highly magnetically permeable material and all of which are conned within said carrying and retaining means, for separating the material of weaker magnetic susceptibility from the nonmagnetically susceptible material;

removing the nonmagnetically susceptible material from proximity with all of the individually movable bodies and from the materials of weaker and higher magnetic susceptibility while all of the m-aterials and all of the bodies are within the relatively weak and relatively strong magnetic fields;

separately collecting the nonm'agnetically susceptible material;

removing the materials of weaker and higher magnetic susceptibility and all of the individually movable 'bodies from the relatively weak and relatively strong magnetic fields;

removing the materials of weaker and higher magnetic susceptibility from proximity wit-h all of the individually movable bodies; and

separately collecting the materials of weaker and higher magnetic susceptibility.

22. An apparatus for separating materials of differing magnetic susceptibility comprising:

at least one magnet means having oppositely disposed -eld poles of opposite polarity for producing an effective magnetic elld therebetween;

a plurality of loose, unattached induced pole pieces, said pole pieces bein-g individually movable relative to each other;

means for carrying and retaining the induced pole pieces;

means for moving the induced pole pieces and the field poles relative to each other so that the induced pole pieces pass into, through and out of the elective magnetic field;

means -for introducing the material to be separated into the effective magnetic field and therein into proximity with the induced pole pieces as the pieces pass through the field; and

means for flushing material from proximity with the induced pole pieces after the pieces have passed out of the effective magnetic field.

23. An apparatus for separating granular materials of differing magnetic susceptibility comprising:

at least one magnet means having oppositely disposed field poles defining a gap therebetween, said field poles being of opposite polarity -for producing an effective magnetic field therebetween;

a movable container disposed within the gap, said container having a foraminous bottom;

a plurality of loose unattached individually movable induced pole pieces disposed within the container and retained therein by the foraminous bottom;

means for moving the container and the induced pole pieces disposed therein relative to the eld poles so that the induced pole pieces successively pass into, through and out of the effective magnetic field;

means for introducing the material to be separated into the effective magnetic field and therein into proximity with the induced pole pieces as the pieces pass through the tield; and

means for iiushing material from proximity with the induced pole pieces after the pieces have passed out of t-he effective magnetic field. 24. A method for separating granular materials of relatively low magnetic susceptibility from materials of relatively high magnetic susceptibility which comprises: moving a plurality of loose-unattacbed individually movable bodies, at least some of which are composed of a highly magnetically permeable material and all of which are contined within a means for `carrying and retaining said bodies, into, through and out of an effective magnetic field; passing la mixture of the materials to: be separated into the effective magnetic field and therein into proximity with the individually movable bodies while the bodies Aare moving through the field so that the material of higher magnetic susceptibility will be attracted toward the highly magnetically permeable individually movable bodies; removing the material of lower magnetic susceptibility from proximity with the individually movable bodies and from the material of higher magnetic susceptibility while both materials and the individually movable bodies are within the effective magnetic field;

separately collecting the material of lower magnetic susceptibility;

removing the material of higher magnetic susceptibility from proximity with the individually movable bodies after the bodies have moved out of the effective magnetic field; and

separately collecting the material of higher magnetic susceptibility.

References Cited UNITED STATES PATENTS 401,414 4/1889 Conkling 209-214 832,825 10/1906 Wait 209-222 1,076,213 10/ 1913 Langguth 209-224 1,576,690 3/ 1926 Ullrich 209-214 2,074,085 3/ 1937 Frantz 209-222 X 2,45 2,220 10/ 1948 Bower 209-224 X 3,021,007 2/1962 Jones 209-232 X FOREIGN PATENTS 160,428 8/1937 Austria.

,1831 3 1900 Germany.

252,035 5/ 1926 Great Britain.

22 6,922 8/ 1943 Switzerland.

HARRY B. THORTON, Primary Examiner. R. HALF-ER, Assistant Examiner. 

